Several designs for rotors adapted to the analysis of whole blood have been disclosed in the past. Such rotors are used with a multistation dynamic photometer of the type having rotatable cuvets. However, each of these have some of a number of disadvantages. A recently disclosed rotor, U.S. Pat. No. 3,901,658, issued on Aug. 26, 1975, which is commonly referred to as the 3-stage, stacked rotor, required six processing and transfer functions to be performed. The step in which a high-density, immiscible liquid was added to the sedimentation bowl to displace the supernatant plasma involved difficulties related to differences in surface tension of the liquids. A small amount of carryover of the oil into the small conduits and cavities of the rotor prevented wetting of the walls by the aqueous plasma phase, with the end effect being blockage of the systems and incomplete transfer of liquids therethrough.
There exists a need for and it would be desirable to provide a simplified rotor for removing cells from whole blood whereby a multiplicity of plasma samples of equal volume can be prepared and transferred to the cuvets in a single operation prior to the addition of reagents. The present invention was conceived to meet this need in a manner to be described hereinbelow.